Draft Environmental Assessment of a Marine Geophysical Survey by R/V Marcus G. Langseth of the Aleutian Arc, September–October 2020 Prepared for Lamont-Doherty Earth Observatory 61 Route 9W, P.O. Box 1000 Palisades, NY 10964-8000 and National Science Foundation Division of Ocean Sciences 4201 Wilson Blvd., Suite 725 Arlington, VA 22230 by LGL Ltd., environmental research associates 22 Fisher St., POB 280 King City, Ont. L7B 1A6 Submitted 27 March 2020 Revised 23 June 2020 LGL Report FA0202-01 Table of Contents TABLE OF CONTENTS List of Figures ............................................................................................................................................... v List of Tables ............................................................................................................................................... vi Abstract ....................................................................................................................................................... vii List of Acronyms ......................................................................................................................................... ix I Purpose and Need ...................................................................................................................................... 1 1.1 Mission of NSF ................................................................................................................................ 1 1.2 Purpose of and Need for the Proposed Action ................................................................................. 1 1.3 Background of NSF-funded Marine Seismic Research ................................................................... 2 1.4 Regulatory Setting ........................................................................................................................... 2 2.1 Proposed Action ............................................................................................................................... 2 2.1.1 Project Objectives and Context ........................................................................................... 2 2.1.2 Proposed Activities ............................................................................................................. 4 2.1.3 Monitoring and Mitigation Measures ................................................................................. 6 2.2 Alternative 1: No Action Alternative ............................................................................................... 9 2.3 Alternatives Considered but Eliminated from Further Analysis ...................................................... 9 2.3.1 Alternative E1: Alternative Location .................................................................................. 9 2.3.2 Alternative E2: Use of Alternative Technologies ............................................................... 9 III Affected Environment ........................................................................................................................... 11 3.1 Oceanography ................................................................................................................................ 12 3.2 Protected Areas .............................................................................................................................. 13 3.2.1 Critical Habitat for ESA-listed Species ................................................................................ 13 3.2.2 Other Protected Areas ........................................................................................................... 14 3.3 Marine Mammals ........................................................................................................................... 15 3.3.1 Mysticetes ......................................................................................................................... 15 3.3.2 Odontocetes ...................................................................................................................... 25 3.3.3 Pinnipeds ........................................................................................................................... 30 3.3.4 Marine Fissiped ................................................................................................................. 34 3.4 Sea Turtles ..................................................................................................................................... 35 3.4.1 Leatherback Turtle ............................................................................................................ 35 3.5 Seabirds .......................................................................................................................................... 36 3.5.1 Short-tailed Albatross ....................................................................................................... 36 3.5.2 Steller’s Eider ................................................................................................................... 37 3.5.3 Spectacled Eider ............................................................................................................... 38 3.6 Corals ............................................................................................................................................. 38 3.7 Fish, Essential Fish Habitat, and Habitat Areas of Particular Concern ......................................... 39 3.7.1 ESA-Listed Fish Species .................................................................................................. 39 3.7.2 Important Fish Resources ................................................................................................. 39 3.7.3 Essential Fish Habitat ....................................................................................................... 41 3.7.4 Habitat Areas of Particular Concern ................................................................................. 42 3.8 Fisheries ......................................................................................................................................... 42 3.8.1 Commercial Fisheries ....................................................................................................... 42 Draft Environmental Assessment for L-DEO Aleutians, 2020 Page iii Table of Contents 3.8.2 Recreational Fisheries ....................................................................................................... 46 3.9 SCUBA Dive Sites and Shipwrecks .............................................................................................. 47 IV Environmental Consequences ............................................................................................................... 47 4.1 Proposed Action ............................................................................................................................. 47 4.1.1 Direct Effects on Marine Mammals and Sea Turtles and Their Significance ................... 47 4.1.2 Direct Effects on Marine Invertebrates, Fish, and Fisheries, EFH, and Their Significance ...................................................................................................................... 70 4.1.3 Direct Effects on Seabirds and Their Significance ........................................................... 78 4.1.4 Indirect Effects on Marine Mammals, Sea Turtles, Seabirds, and Fish and Their Significance ...................................................................................................................... 78 4.1.5 Possible Effects on Subsistence Hunting and Fishing ...................................................... 79 4.1.6 Direct Effects on Cultural Resources and Their Significance .......................................... 80 4.1.8 Cumulative Effects ........................................................................................................... 81 4.1.9 Unavoidable Impacts ........................................................................................................ 84 4.1.10 Coordination with Other Agencies and Processes ............................................................ 85 4.2 No Action Alternative .................................................................................................................... 85 V List of Preparers ..................................................................................................................................... 86 VI Literature Cited ..................................................................................................................................... 87 List of Appendices .................................................................................................................................... 134 Appendix A: Determination of Mitigation Zones .................................................................................... A-1 Appendix B: Marine Mammal Densities ................................................................................................. B-1 Appendix C: Marine Mammal Take Calculations ................................................................................... C-1 Appendix D: Ensonified Areas for Marine Mammal Take Calculations ................................................. D-1 Draft Environmental Assessment for L-DEO Aleutians, 2020 Page iv List of Figures LIST OF FIGURES Page FIGURE 1. Map of the proposed 2020 seismic survey of the Aleutian Arc showing representative survey lines and marine